Young child with conduct disorder

I posted this in the ADHD forum as well, but quickly I will say he is 5 years old, doesn't listen to adult authority, kicks, bites, cuts, and claws others. He has uttered serious threats, life threatening threats against his family, his classmates and friends. He is abusive to his classmates boys and girls alike, and to his dogs and shows very little if any empathy or remorse for his abusive actions.
The doctor told my sister if he isn't treated asap he fears he will have early incarceration and end up in the prison system at an early age for arson, for hurting himself or others.

Thread proceeds here:

attention-deficit-hyperactivity/topic44223.html

Kevin